1. Field of the Invention
This invention relates to a chuck device for a dental handpiece.
2. Prior Art
Conventionally, there have been various types of chuck devices of this kind available commercially, but because they are either large in deflection of axis of a cutting tool shaft or high insertion pressure when the cutting tool is inserted, they present a number of problems such as the bent shaft of a cutting tool, a broken cutting edge, lack of durability, short service life, etc. In the case of such chuck devices it is usually necessary to send the handpiece back to a factory specializing in the production of such chuck devices, either to repair or replace the chuck in question each time replacement of the chuck is needed. The inconvenience involved is very great. In view of such circumstances, a so-called cartridge type collect chuck which premits replacement of chucks by users themselves and which is relatively high in durability is used by some users, but even this collect type chuck still has the fatal disadvantage that the chuck needs the trouble of tightening and loosening the screw everytime the cutting tool is attached and detached and that it has a possibility of the cutting tool being flung out to cause accidents when tooth cutting is carried out without sufficiently tightening the screw.